The present invention relates to an apparatus and a method for adjusting a minute positional displacement or error between a working unit which is mounted to an industrial robot and a workpiece.
Recently, there have been provided many kinds of industrial robots, and there is known the industrial robot provided with the working unit for carrying out arc welding operation or drilling operation. For example, the Japanese Patent Laid-open No. 62-183969 discloses an arc welding robot which is provided with a welding position detecting device. The welding position detecting device of this type generally includes an irradiation optical unit and an observation optical unit for adjusting the focus position of the observation optical unit by detecting the position and the amount of a scattered light obtained by irradiating a light beam on a reference surface.
According to the welding position detecting device of the type described above, a position of a welding line along which a welding operation is carried out, is detected by irradiating the light beam having a different wave length from that of a sectorially converging light on the optical axis of the converged light. A position of a welding torch is controlled in accordance with detected results. Accordingly, it becomes difficult to adjust the minute positional errors or displacements between the welding torch and the workpiece.